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UPV Theses and Dissertations

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    Antimicrobial activity of macrofungal basidiomycetous mycelia against Vibrio spp.
    Bagacay, Jann Felnesh Exe V. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2023-06)
    Aquaculture is vital for global food security, producing 50% of the world’s fish. However, infectious diseases caused by fish pathogens like Vibrio species can lead to significant production losses. To address this issue, antimicrobial agents are commonly used. Macrofungal fruiting bodies and mycelia produce bioactive compounds with antimicrobial properties. This study aims to: (a) assess antimicrobial activity in isolated macrofungal samples against the fish bacterial pathogens Vibrio parahaemolyticus and Vibrio cholerae, (b) compare two methods (agar plug and crude extracts) for antimicrobial activity, (c) determine the minimum inhibitory concentration (MIC) using agar well diffusion and the agar plug methods, and (d) identify the macrofungal isolate with the highest antimicrobial activity. Ten morphospecies were collected from the University of the Philippines Visayas Miagao Campus. The samples were evaluated using the agar plug and agar well diffusion methods. The results showed antimicrobial activity against Vibrio cholerae and Vibrio parahaemolyticus. The activity index ranged from 0 to 0.83 and 0.22 to 0.78 for agar wells, and 0 to 1.00 and 0.70 to 1.30 for agar plugs, against V cholerae and V. parahaemolyticus, respectively. Termitomyces globulus and Trametes sp. 1 exhibited the highest activity indices using the agar plug and agar well diffusion methods, respectively. Statistical analysis confirmed significant differences in antimicrobial activity against both test organisms. These findings demonstrate the potential of macrofungi as a valuable source of antimicrobial compounds for controlling fish pathogens in aquaculture. Further research could lead to the identification and utilization of these compounds to minimize production losses and improve disease management in aquaculture.
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    Phytochemical, antioxidant, and antibacterial analysis of essential oils from Zingiber officinale Roscoe(Ginger) and Curcuma long Linn.(Turmeric)
    Alviar, Joseph Noel G. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    This study was conducted to characterize and compare the phytochemistry, antibacterial and antioxidant activities of essential oils extracted from the rhizomes of Zingiber officinale Roscoe (ginger) and Curcuma longa Linn. (turmeric). Percent yields in the steam distillation of ginger and turmeric were 0.42±0.02% and 0.43± 0.02%, respectively. Qualitative phytochemical screening showed that both essential oils are positive for flavonoids, phenols, saponins, terpenoids, tannins, and quinones. Antibacterial activity was tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli using 100%, 75%, 50%, and 25% (v/v) essential oil in ethanol with positive control tetracycline and negative control ethanol. It was determined that C. longa did not have antibacterial activity against both bacteria while Z. officinale had “moderately inhibitory” to “strongly inhibitory” activity against S. aureus with zone of inhibition (ZOI) from 17.67±1.53 mm to 23.67±0.58 mm and “weakly inhibitory” to “moderately inhibitory” activity against E. coli (ZOI from 12.33±1.15 mm to 15.67±2.08 mm). The standard antibiotic tetracycline also showed “moderately inhibitory” activity against both S. aureus (ZOl = 19.00±0.89 mm) and E. coli (ZOI = 17.33±1.21 mm). Antioxidant activity was determined by DPPH free radical inhibition. Highest % DPPH free radical inhibition was exhibited by the standard antioxidant ascorbic acid (92.98%), followed by C. longa essential oil (88.74%), and Z. officinale (76.30%).
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    Chromatographic analysis and antibacterial assay of Avicennia officinalis bark extracts
    Janagap, Steve P. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2003-04)
    In this study, the antibacterial activity and the chemical constituents of Avicennia officinalis bark were determined. The antibacterial assay showed that the dichloromethane (DCM) fraction at 1000 ug/mL was most effective against the tested bacteria especially to Staphylococcus aureus. It had a microbial index of 0.97 while the positive control, amoxicillin had 1.00. The aqueous fraction did not show antibacterial activity to the organisms tested. A number of chemical constituents were found to be present in the different fractions obtained from Avicennia officinalis bark: alkaloids, cardiac glycosides, flavonoids, phenolic compounds, saponins and terpenes. These constituents were determined using thin layer chromatography. The DCM fraction which showed the highest bioactivity, had the most number of components while the aqueous fraction had the least number of components. The DCM fraction was subjected to two-dimensional thin layer chromatography. Nine spots were observed with the first solvent system (ethyl acetate-DCM; 5:3) while eleven spots were observed with the second solvent system (ethyl acetate-n-hexane-DCM; 2:1:1).